MoO3—H2体系气相反应制备超细钼粉

1 绪言超细金属粉末广泛应用于许多领域.在电子器件中,细颗粒钼粉用于制备导电薄膜,为了达到此应用,控制粉末特性是很重要的. 在本研究工作中,对MoO_3-H_2体系的气相反应制取超细钼粉作了研究,并着重研究了颗粒尺寸与制备工艺条件之间的关系.     

在高温下用氧将MoO2氧化成MoO3的动力学

在温度为 674～ 791Ｋ和氧分压为 8.1～ 30 .4ｋＰａ时 ,研究了ＭｏＯ2 氧化成ＭｏＯ3的动力学 ,用微电子微天平测定了反应时重量的增大。反应相对于氧浓度为 0 .6级 ,而活化能为 1 48ｋＪ/ｍｏｌ。所得数据能更好地弄清ＭｏＳ2 的氧化动力学。将反应时间加和的规律应用于各颗粒 ,获得一个转化分数与时间关系的方程。此方程可应用于等温条件下 ,或者应用于非等温条件下反应气体扩散过多孔产物薄层。温度的升高是反应放热的结果 ,且可用体系热平衡来计算。同时 ,研究了结块和裂缝的形成对转化分数的影响。在ＭｏＳ2 焙烧时的设备设计和操作条…     

MoO3对染料光催化降解性能研究

分别在太阳光、红外灯光、荧光灯光不同光源照射下，用仲钼酸铵硝酸分解法和热分解法制备MoO3，对几种常见染料光催化降解性能进行了研究。研究了溶液的酸度、催化剂的用量、光照时间等不同条件对染料脱色率的影响．结果表明，用仲钼酸铵硝酸分解法制备的MoO3在酚藏花红、罗丹明B、甲基紫等染料的光催化降解过程中催化活性好，脱色率可达90％以上；将使用过的MoO3重复实验，其光催化活性基本不变，性能稳定，可重复使用；加入Fe^3 ，H2O2等其他物质可提高染料的脱色率；对染料原溶液和脱色后的溶液进行紫外一可见光谱分析，发现染料脱色确实由光催化降解所致。     

Synthesis, Structure and Ionic Conductivity of La2／3-x Li3x MoO4

AlargenumberofM0 .5A0 .5M′O4 (M :rareearthion ,Bi3+,Fe3+,Cr3+,etc .A :alkaliion ,Cu+,Ag+,etc .M′ :Mo ,W )withtetragonalscheelite typestructurehavegoodcatalyticproperties .Aslumines centsubstrates ,theyhaveexcellentsensitizationtolu minescenceofrareearthion .Manyresearchesontheirstructure ,catalytic ,magneticandluminescentproper tieshavebeenmadesince 196 0s[1～ 10 ] .Thegeneralformulaforcompoundswiththetetragonalscheelite typestructureisAM′O4 wherethecationM′istetrahe drallycoordinat…     

正交晶系MoO3(β-MoO3)的结构特征及其应用

简述了MoO3两种结晶体α-MoO3和β-MoO3的物理性质及结构特征，并对β-MoO3的生产、热稳定性及用途作了重点论述。     

Na2MoO4固—固相变的DTA—TG测定

利用DTA－TG热分析技术研究了无机塑晶材料Na2MoO4的热性能。实验数据表明,Na2MoO4的固－固相变焓为201．4J／g,是一种有前途的固－固相变贮能材料。固－固相变的机理是随着温度的升高,Na2MoO4晶体的晶格发生畸变,晶型由低对称的晶系向高对称的晶系转变,同时引入振动和转动无序,从而吸收热量。     

电场碱分解工业MoO3的碱浸流程研究

用交变电场碱分解的碱浸流程取代酸洗流程和传统的碱浸流程,这一改进流程既不同于酸洗流程,也不同于传统的碱浸流程。其主要优点是：钼的回收率高,生产成本低,能生产各种纯度的钼酸盐产品,无污染,有利于环境保护和可持续发展。     

添加剂对氧化钼(MoO3)高温挥发的影响

实验表明，从600—1100℃加热5min时，单纯块状氧化钼（MoO3）挥发率达30％，粉状氧化钼挥发率高达40％。CaO与MoO3反应生成CaMoO4，从而降低MoO3的活性，因此加入CaO可抑制氧化钼的挥发。随着CaO加入量的提高，氧化钼挥发率下降，当CaO加入量达20％时，氧化钼挥发率降至1．0％。白钨矿也能抑制氧化钼挥发，抑制效果低于CaO。Al2O3和SiO2不能抑制氧化钼的挥发。     

Synthesis and spectral characteristics of La2MoO6：Ln3＋ （Ln=Eu, Sm, Dy, Pr, Tb） polycrystals

The novel phosphors of La 2 MoO 6 activated with the trivalent rare earth Ln 3+ (Ln=Eu, Sm, Dy, Pr, Tb) ions were synthesized by solid state reactions at high temperature in air atmosphere, and their phase impurities and luminescent properties were studied. The photoluminescence (PL) excitation and emission spectra, and decay curves were employed to study their luminescence properties. The lifetimes of the characteristic emissions from Ln 3+ ions were in the order of millisecond except Pr 3+ ions. (LaEu 1-x ) 2 MoO 6 was a promising phosphor for practical application and the optimum concentration was x=0.075. The concentration quenching mechanism of Eu 3+ was also discussed by theoretical fitting using Burshtein model.     

低温液相合成路线制备六方相MoO3纳米棒

以钼酸钠为原料,通过简单的液相脱水反应,首次在常压、较低温度下大规模合成了介稳的六方相MoO3纳米棒.用x-射线衍射,透射电子显微镜、场发射扫描电子显微镜、高分辨透射电子显微镜等对所制备的样品进行表征.结果表明,所制备的样品为纯的六方相MoO3纳米棒,直径约100～400 nm,长度可达几个微米,纳米棒沿着六方相MoO3(101)面的法线方向生长.同时,实验结果表明,所制备的MoO3样品对亚甲基蓝溶液表现出良好的光催化降解性能,实验条件下,最大脱色率可达到94.7%.     

氢气还原蒸发态MoO3制取超细钼粉的探索

考察了温度、时间等因素对三氧化钼挥发率的影响。对氢气还原蒸发态三氧化钼制取超细钼粉的工艺进行了探讨，初步研究了氢气还原三氧化钼蒸汽的动力学规律，初步确定了氢气还原三氧化钼蒸汽制取细钼粉的工艺条件。     

Ti—15V—3Cr—3Sn—3Al合金研究

研究了Ti-15V-3Cr-3Sn-3Al合金的冷轧变形、热处理及其对合金组织和性能的影响。试验结果表明:该合金具有优异的冷轧变形能力,当冷轧变形量达70%时,板材边缘仍无裂纹产生。800℃固溶处理不同冷轧变形程度的板材,拉伸强度无明显变化,而对延伸率有一定影响,当变形量达30%以上时,延伸率增至稳定值。该合金的β转变温度约为750℃,当在此温度以上固溶处理时,晶粒尺寸随温度提高而长大,但长大速度甚缓。时效温度对Ti-15V-3Cr-3Sn-3Al合金的拉伸性能影响显著,合金强度随时效温度提高而降低,延伸率则提高。测试了Ti-15V-3Cr-3Sn-3Al合金的高温拉伸性能和300℃的热稳定性能,说明该合金可在时效状态下长期使用。     

Flux and concentration effect on Eu^3＋ doped Gd2（MoO4）3 phosphor

A novel red emitting phosphor Gd2（MoO4）3：Eu^3＋ was prepared by solid reaction, using Gd2O3, Eu2O3 and WO3 as starting matedals and NH4F as flux. The effects of flux content and Eu^3＋ concentration on the crystal structure, morphology and luminescent properties were investigated using XRD, SEM and fluorescent spectrum measurement. The XRD patterns showed that the resultants had the monoclinic structure. With the increase in flux amount, their crystallization significantly improved. The SEM images indicated that the mean size of the phosphor particles was around 2 μm, and agglomeration of the phosphor particles appeared while introducing higher flux amount. The excitation spectra exhibited more intense f-f transitions originating from ground state 7^F0 to upper states 5^L6 and 5^D2 than the charge transfer band. The concentration quenching of Eu^3＋ emission indicated that energy transfer from Eu^3＋ to molybdate host existed even at lower Eu^3＋ concentration.     

过氧钼酸溶胶制备的MoO3纳米带及其电化学性能研究

以过氧钼酸溶胶为反应前驱体采用简单的水热方法，在没有任何模板剂的条件下合成三氧化钼纳米带，通过XRD，SEM，TEM和IR等测试方法对产物进行结构表征和形貌分析。结果表明，MoO3纳米带的宽度为100～500nm，平均厚度为70nm，长度可达十几μm；其电化学实验结果表明，MoO3纳米带的首次放电比容量可达310mAh·g^-1，循环10次后其放电比容量为265mAh·g^-1，容量保持率达85．5％，循环性能优良。     

Growth and characterization of ferroelectric Tb2（MoO4）3 crystal

By using Zb4O7 and MoO4 as starting materials, ferroelectric Tb2(MoO4)3 crystal was grown by the Czochralski method. The as-grown crystal was pale green color, transparent and crack-free. X-ray powder diffraction (XRPD), transmission spectrum, dielectric con-stant and polarization-electric field (P-E) hysteresis loop measurements were performed to characterize the crystal. The XRPD confirmed the as-grown crystal to be Tb2(MoO4)3. The transmission spectrum of the crystal showed that its transmittance in the entire visible and most near-infrared region was more than 70% except for an absorption peak around 486 nm. Obvious dielectric anomaly could be observed at low frequencies with increasing temperature through the dielectric constant measurement and the Curie temperature of Tb2(MoO4)3 crystal was determined to be 162.3℃. The unsaturated P-E hysteresis loops indicated that it was difficult for the ferroelectric domains in Tb2(MoO4)3 crystal to array regularly with repeated switching of the electric field.